Switch and tuning device for radio transceivers



y 1950 DE WlTT R. GODDARD 2,513,796

SWITCH AND TUNING DEVICE FOR RADIO mmnscmvms Filed Oct. 4, 1945 INVENTOR05 W77 ooa/wa.

ATTORNEY Patented July 4, 1950 SWITCH AND TUNING DEVICE FOR RADIOTRANSCEIVERS De Witt R. Goddard, Riverhead, N. Y., assignor to RadioCorporation of America, a corporation of Delaware Application October 4,1945, Serial No. 620,347

4 Claims. 1

This invention relates to means for tuning a transceiver, andrforswitching the. circuits thereof between receiving. and transmittingconditions.

In two-way'ra'dio telephone sets it is customary to provide a push-to-talk key or button wherebythe circuits" of the transceiver may be alteredand at the same'time the frequency of the oscillator" maybe shiitedto"that of the assigned outgoingcarrier' wave.

It is' an object of my invention to provide a simple mechanical slidingbutton to substitute' for'the'prior art type of push to talk button. Thepresent invention provides a novel sliding device having theunit-control function of shifting the frequency of an oscillator in atransceiver so as tocondition the oscillator for producing the carrierwave when transmitting, and of re-tunin'g theoscillator for reception soas to producesuper-regeneration, the sliding device being simultaneouslyeffective in performing a switching operation;

This application deals with novel means for switching the circuitconnections of high frequency transmitters and receivers for operationat one time asa transmitter and at another time as a receiver, suchmeans being combined with a tuning device which is readily adjusted toany desired frequency for reception while being instantly shiftable toanother frequency suitable for transmission;

My invention will now be'described in more detail, reference being madeto the accompanying drawing in which? Fig.1 showsla view of the switchand tuning device as it appears with the instrument cover removed; A

Fig. Z'shows another viewof. the same arrangement but with the switchand tuning deviceshifted to the talk? position; and

Fig. 3 shows in perspective the mounting for a short-circuited' tuningring which is variably positionable in relation tothe tank circuitwinding of an antenna transformer.

Since like parts are given the same reference numerals indifferentfigures of the drawing, reference may be made from one figure to.another according. to the needs of the description to follow, for bestillustrating, the invention.

The complete transceiverrunit,except for the antenna, earphones. andbattery, is assembled in compact form within a case I. At. one end ofthis case is a receptacle 2 into which an antenna may be plugged; Theterminals of the receptacl'e are connectedto. a loop 3" which. consti 2tutes one inductive member of an antenna transformer. The end-of thisloop is in:coupling,relation to a tankecircuit winding 5. The terminalsof Winding 5 are suitably connected between the anode and grid of anoscillator tube (not shown) The other components of the oscillatorcircuit are conventional anddo not constitute essentialparts I oftheinstant invention.

A tuning loop 4 is mounted in coupling relation to the tank coil 5. Themounting is-by means of a swiveledinsulating block 6. A pivot post 1 forthe block 6- is firmly affixed to the casing of thetransceiver.- Aroundthe post i I preferably position acoiled spring 8, one end of which isattached at the top of. the post and the other. end is secured to theinsulating block 6 at a point intermediate its two ends. The tension onthe spring 8 is arranged to swing the block 6 counterclockwise and tobring the tuning coil 4 as close to the tank coil 51 as may be permittedby one or the other of two stops 9 and it Stop 9 is at the-end of a pushrod H which isunder. control of. a.s1iding button l2. to be used as a'push-to-talk button.

The other stop I0 is at one end of a push-rod I3 which. is. arranged to:be actuated by a rotatable tuning knob l4. Thetuning knob is showndottedbecause it-is outside of the case, but it is swiveled. on a. shaftwhich also carries a disc l5 within the case. An eccentric pin 16 on thedisc l5- constitutes. a pivot. bearing for one end of the push-rod l3.Concentric with the. disc l5 and mounted thereon is another. pin H whichserves as a stop to prevent over-travel of the push-rod l3 beyond adesirable limit correspond-. ing to the low frequency endofithe tuningrange forthe oscillator as used" for super-regenerative The rod llcarries two slidling contact plates I 20 and 21; which serve tointerconnect certain switch terminals off'a double-pole-double-throwswitch. The switching functions performed in order to condition thenormally receptive circuit for transmission involve closing. a circuitfrom contact 22 to contact 23-, and also transferring the connection ofcontact from contact 25to contact 26'; The pushbutton l2 performs thisThese openings in the v of a spring 3i.

service whenever the thumb of the operator drives this button to theright. Fig. 2 shows the button I2 and associated rod H moved to theright, which is the talking position.

In a preferred arrangement of the push-button control for the switch barH the button 12 is mounted on a plate which slips forward and back onthe outside of an edge wall of the case cover. Inside of this wall is aretaining strip which is fastened to the outside plate by means of twoscrews 21 and 28. These screws are fitted with nuts on the inside inorder to hold the plates together and allow a free sliding movement ofthe push-button. Screw 21 is longer, however, than screw 28 in orderthat it may serve to engage a pin 30 on the push-rod ll. When operatingthe push-button E2, the push rod H is moved to the right in oppositionto the tension Upon releasing the push-button l2, the push-rod isrestored by the tension of the spring 3| to the position for receiving.

In the operation of my tuning means as above described, the tuning knobI4 is turned to the correct position for tuning the oscillator circuitto such frequency as will produce super-regenerative reception. Thistuning operation sets the short-circuited loop 4 in proper position, towhich it will be automatically returned after each release of thepush-to-talk button. The displacement of the short-circuited loop 4 byoperation of the push-button is provided by the swinging of itsinsulation mounting block 6 to an extreme position, which isdeterminedby the striking of a pin 32 against the partition wall I9. Pin32 may be the same pin which holds the spring 3|, the other end of thespring being mounted on a stationary post afiixed to the chassis.

It should be noted that the means provided for switching from listeningto ftalking conditions is combined with the adjustment of theshortcircuited loop 4 in a very simple but novel manner. It is wellknown that a short-circuited loop may be used in this fashion tovary thefrequency of an oscillator. V

The range of, frequencies available for tuning the receiver is thatwhich is obtained bythe movement of the short-circuited loop 4 underspring tension between two limits. quency of the oscillator is obtainedwhen the loop 4 is nearest to the tank coil 5. This position isdetermined by the stop 9 on the end of the push rod H when the latter isheld in normal position by the tension of spring 3|. The lowestfrequency to be used for reception is obtained when the insulating block6 is rotated clockwise by the rod l3 until the latter butts against thepin l! at for producing the desiredtransmittingcarrier wave.

One drawback of the pastwhich has been overcome by the adoption of my.invention is that there is no longer any tendency for two transceiversin communication to"walk the frequency up. This difficulty was caused byretuning the transceiver each time it started to receive. Then, upontransmitting, the oscillator delivered a higher frequency than before,due in part to the higher anode voltage applied to the oscillator whentalking, and eventually the carrier wave passed out of the assignedcommunication channel. In other words, each time a shift was made Thehighest frefrom receiving to talking the previous adjustments were lost,and attempts to restore the assigned frequencies were not alwayssuccessful. With the aid of the invention herein disclosed, the carrierfrequency remains fixed for two transceivers in communication, andthereis no tendency for tuning adjustments to be displaced when operating thepush button.

In practice my system will allow a plurality of transceivers to beadjusted so that they all transmit on a predetermined assignedfrequency. These transceivers may then be operated independently,maintaining communication with each other without deviating from theoriginal frequency.

What is claimed is:

1. In a radio transceiver, a transformer coil in a'tank circuit which istunable to a radio frequency carrier wave, a closed'loop disposed inreactive coupling relation to said coil, pivoted means for supportingsaid loop, a resilient member for urging said pivoted means and its looptoward the tank circuit, two push-rods effective to press against saidpivoted means in opposition to the force of said resilient member, atuning device manipulatably operable to setone of said push-rods,thereby to fix the degree of coupling between said coil and said closedloop suitably for obtaining a super-regenerative receiving condition insaid transceiver, and a sliding mechanism operable upon the other ofsaid push-rods to cause that amount of diminution in the degree ofcoupling, whereby the tank circuit is tuned to the frequency of thecarrier wave which is to be transmitted.

2. In a device according to claim 1 a plurality of stationary andmovable switch components constituting means for conditioning thecircuits of said radio transceiver either to receive or to transmit, themovableswitch components being mounted on that one of the push-rodswhich. is operable by said sliding mechanism.

3. In a two way radio apparatus, a sliding operating member, a springtensioned pivoted arm disposed so as to be actuated by an end of saidmember, movable switch contact means carried by said member, a movabletuning loop located on an end of said arm, a tuning coil inductivelycoupled to said loop, fixed contact means for engaging said movablecontact means, said member acting to shift said arm to thereby vary thetuning of said apparatus, resilient means secured to said member andacting to oppose the, move ment of said member, and a transmit-receivesystem controlled by said contact means, said system including anoscillator whose tank circuit includes said tuning coil.

4. In a two-way radio apparatus, the combin a tion with a manipulatablesliding mechanism of switching means operable by suchmechanism tocondition the circuits of said apparatus for transmitting a modulatedcarrier wave of predetermined frequency, a short-circuited loop couplingmember inductively coupled to a tank circuit which is one Of thecomponents of said radio apparatus, said member being adjustably mount,-ed with respect to said tank circuit and being adjustable to a normalposition relative thereto which permits of super-regenerative receptionof signals having the frequency of said carrier wave, means operable bysaid mechanism for adjusting said member relatively to said tank circuitto a position which fixes the frequency of the transmitted carrier wave,and resilient means for biasing said member toward said normal position,sa d res li nt means operating in response to 5 2 release of saidmechanism to restore said member Number to said normal position.2,153,205 DE WITT R. GODDARD. 2,187,340 2,288,214 REFERENCES CITED 5 ,41,794 The following references are of record in the file of this patent:

Number UNITED STATES PATENTS 470,366 Number Name Date 10 512,1212,018,569 Pettengill et a1 Oct. 22, 1935 550,774 2,126,868 Brown Aug.16,1938

Name Date Park Apr. 4, 1939 Wilhelm Jan. 16, 1940 Summers June 30, 1942Crosby Mar. 4, 1947 FOREIGN PATENTS Country Date Great Britain Aug. 13,1937 Great Britain Aug. 29, 1939 Great Britain Jan. 25, 1943

